Unusual three-star system promises new test of gravity

Measurements of pulsar and white dwarfs could bolster or dethrone general relativity

TRIPLE THREAT A pulsar (left) is orbited by two white dwarfs — one close in, one farther away — in this illustration of the system PSR J0337+1715. The curved blue lines show the pulsar’s magnetic field and the blue cones show the radiation the star sends into space. Astronomers measuring this radiation will try to test general relativity, the leading theory of gravity, to unprecedented precision.

A unique threesome of stars locked in tight, circular orbits could help astronomers test the leading theory of gravity to unprecedented precision. The discovery of the celestial trio is reported January 5 in Nature.

“We should be grateful to the universe for making such things,” says Paulo Freire, an astrophysicist at the Max Planck Institute for Radio Astronomy in Bonn, Germany, who applauds the finding. “Part of me wishes I were involved.”

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